The broad goal of our 10 year project has been to study influences from a developing child's social environment on certain adolescent "transition behaviors." During years 8-10 we are conducting an Intra-Generational Study using the NLSY-Youth that considers several types of family influence On important transition behaviors--sexuality, smoking, drinking, and delinquency. We combine two innovations in this research. First, we have recently identified previously undefined kinship links in the NLSY data for a number of different levels of biological relatedness. Second, we have extended a behavioral genetic approach -- DF Analysis (DeFries and Fulker, 1985) -- that permits control of genetic influences in the assessment of environmental influences. Separate theoretical extensions of DF Analysis account for both shared and nonshared environmental influences. The NLSY files are being used to construct a number of measures that will be used to test hypotheses of family environmental influence. In previous work we applied DF Analysis using the kinship links in the NLSY-Children dataset. The development of an algorithm to define genetic links among the original NLSY-Youth supports research on transition behaviors with this new methodology in a more broadly generalizable sample. Past research on the social influences on transition behaviors has not adequately accounted for genetic and environmental sources of confound, as we can with these data and methods. Our models unite a number of distinct sources of genetic and environmental influence into a single coherent analytic scheme.